Liquid cleaning compositions are often considered to be more convenient to employ than dry powdered or particulate products and, therefore, have found substantial favor with consumers. They are readily measurable, speedily dissolved in water, capable of being easily applied in concentrated solutions or dispersions to soiled areas to be cleaned and are non-dusting, and they usually occupy less storage space. Furthermore, liquids are more environmentally sound since they eliminate the requirement for organic salts, including phosphates, and enable a reduction in waste volume. Additionally, the liquid cleaning compositions may have incorporated in their formulations materials which could not stand drying operations without deterioration, which materials are often desirably employed in the manufacture of particular cleaning products.
The unit packaging of cleaning compositions in sachets has already been proposed in the literature, but in practice, bulk packaging of both powdered and liquid cleaning compositions in cartons, drums, bottles and the like is generally employed. However, wastage or underdosage tends to occur when the consumer is left to judge the correct amount of a product to use. Unit packaging alleviates these problems and also avoids skin contact with the cleaning composition, so that more highly alkaline and acid compositions can be used.
Sachets for unit packaging of detergent powders are disclosed in U.S. Pat. No. 4,188,304, which discloses sachets of water-insoluble, water-permeable material, which are clearly unsuitable for the packaging of liquids, and sachets designed to open in use. The latter type of sachet requires seals that are sensitive to the wash water, and they would accordingly be unsuitable, in general, for the packaging of liquids.
U.S. Pat. No. 3,277,009 discloses packets made of water-soluble film and their use for the packaging of, inter alia, solid detergent compositions and non-aqueous liquids such as petrol and carbon tetrachloride. Such packets were clearly considered unsuitable for packaging liquids having an appreciable water content since such liquids would have been expected to attack the packet walls.
Some have proposed to solve this problem by providing the cleaning composition in the form of a paste or gel which will not dissolve the film. However, liquid cleaning compositions possess advantages over pastes and gels, including faster delivery and dispersability of the cleaning ingredients.
Others have proposed coating the internal walls of the packet with water-resistant materials, such as a waxy or oleaginous material (see, e.g., U.S. Pat. Nos. 3,186,869 and 3,322,674) or a layer of plastic (see, e.g., U.S. Pat. No. 4,416,791). Unfortunately, such packets are more difficult and expensive to produce than simple, uncoated packets.
Still others have proposed multilayered packets comprising a combination of water-soluble and water-insoluble layers. For example, U.S. Pat. No. 3,790,067 discloses a disposable container having an inner layer of water-insoluble polymeric film material and an outer layer of water-soluble polymeric material. The outer layer is relatively strong, and the inner layer is sufficiently thin to be shredded under normal atmospheric forces, or the weight of material in the container, once the outer layer has dissolved away. Again, such packages are more difficult and expensive to produce than simple, uncoated packages.
U.S. Pat. No. 4,973,416 discloses an aqueous liquid laundry detergent comprising from about 10% to about 24% by weight of water and a substantially organic neutralization system which is contained in a package, preferably a pouch or packet containing a unit dose of said liquid laundry detergent, said package comprising a water soluble film-forming material. Compatibility of the liquid laundry detergent with the water-soluble film is said to be achieved by the use of a critical water level in the liquid laundry detergent in conjunction with a substantially all organic neutralization system.
The patent also teaches the use of a solvent system which is comprised of an alkanol, for example, ethanol and/or a polyol, for example, propylene glycol, which operates in conjunction with the water in the liquid laundry detergent can be used to enhance the compatibility of the liquid laundry detergent with the water-soluble film and to ensure the isotropic nature of the liquid laundry detergent.
All references, including patent documents, cited herein are hereby incorporated by reference herein in their entireties.